GtkSolver - Linear System of Equations Solver written in C and Gtk+2.
GtkSolver is a simple but fast and capable linear system solver that is simply a GtkTextView wrapped around a command-line solver to allow simple copy/paste of the coefficent matrix (including the constant vector as the last column) into the textview editor for solving. Basically it is an editor with a [Solve...] button. A convenience that saves creating the file with the coefficent matrix and constant vector before calling the solver from the command line. The underlying parser and solver is written entirely in C. (the mtrx_t.[ch] source files contain code for handling direct file input as well)
The linear system solver uses Gauss-Jordan Elimination with full pivoting to solve a system of equations containing any number of unknowns up to the physical memory limits of your computer. See Gaussian Elimination Though the buffer for each line of the coefficent matrix parsed from the textview is limited to 8192 characters. If your needs are greater, just change the MAXC define at the top of mtrx_t.h.
The interface is straight forward. The program lauches with a short help message and example of the input format expected in the textview itself. Simply paste your coefficent matrix with the constant vector as the final column replacing the help message and click [Solve...]. Or if you need to middle-mouse paste from your select-buffer, the [Clear] button allows you to clear the textview and without disturbing the contents of your select buffer.
(note: [Solve...] will be grayed (inactive) until you make changes to the buffer, and will return to inactive state after each solution until the buffer is change for the next solver run)
The contents of the textview (i.e. the GtkTextBuffer) is read and passed to the solver. The input format is flexible, but must be an [N x N+1] matrix (representing N equations and N unknowns PLUS the constant vector as the last column). Delimiters between the values are ignored. All values are processed as type double. (as defined in mtrx_t.h)
The contents of the textview before pressing [Solve...] is flexible and could equally be:
3.0 2.0 -4.0 3.0
2.0 3.0 3.0 15.0
5.0 -3.0 1.0 14.0
or
linear system of equations:
3 2 -4 | 3
2 3 3 | 15
5 -3 1 | 14
or
3,2,-4,3
2,3,3,15
5,-3,1,14
(all leading characters that are not ".+-[0-9]" are discarded, so the line and leading whitespace in the second example above "linear system of equations:" is ignored)
Clicking [Clear] clears the GtkTextBuffer, and clicking [Help] clears the buffer and redisplays the initial help message.
Taking the contents of the second example above as the contents of the textview and clicking [Solve...] results in:
linear system of equations:
3 2 -4 | 3
2 3 3 | 15
5 -3 1 | 14
Solution Vector:
x[ 0] : 3.0000000
x[ 1] : 1.0000000
x[ 2] : 2.0000000
(where the formatted solution vector is simply written back to the same GtkTextBuffer and displayed in the textview below the coefficent matrix)
The button bar on the bottom has been removed from the default interface and replaced with a standard menu and toolbar. If you liked the old button bar you can enable it simply by passing the '-b' option on the command line to turn the bottom button bar on. If you don't like the new toolbar, you can turn the toolbar off by passing the '-t' option on the command line. The static label across the top basically duplicating the titlebar text has been removed.
For Linux, all that is needed is gcc/make/pkg-config and Gtk+2. (note: some distributions package the headers and development files in separate packages, for instance Gtk+2-dev). You may want to create an out-of-source directory for building to prevent cluttering your sources with the object and executable files. Simply create a separate directory (e.g. gtksolver.build) and then symlink the Makefile, src and include directories within your build directory. All that is needed then is to change to the build directory and type:
$ make
For building on Windows, see the notes on obtaining the precompiled Gtk libraries and header files in the Compiling Section of GtkWrite Readme.md. (note: you do not need the gtksourceview libraries or headers) You will also need MinGW installed.
Building with MinGW on windows:
$ make os=windows
(the os=windows simply appends .exe to the executable name so that strip finds the executable correctly.)
Building with TDM-MinGW on windows.
TDM-MinGW is often installed as part of the Code::Blocks IDE. The only addition for using TDM-MinGW is to pass the CC=mingw32-gcc make-variable on the command line and invoke make with mingw32-make to accommodate naming difference in TDM-MinGW, e.g.
$ mingw32-make CC=mingw32-gcc os=windows
There is nothing required for the solver to run other than invoking the executable. The solver and interface is fully funciton without more. However, for it to find and display the GtkSolver icon, currently the img/ directory must be installed below the current working path for the executable. The LICENSE file should be in the working directory. Eventually there will be additions to determine the system and user paths and to set a standard install location for the image and license files when gtksolver is packaged for the various distributions.
As mentioned at the beginning, this project is basically a quick GtkTextView wrapper around a linear system solver. The Gtk+2 interface and forwarding of the textview contents to the solver has minimal validations. This basically grew out of finding a convenient way to help students with physics and engineering problems. The acceptable input format is flexible enough to allow pasting of a .csv (comma separated values file) into the editor window or any other delimited set of numbers that make up the coefficent matrix for a system of equations. The underlying solver and parsing code is much more robust.
In addition to the Gtk+2 interface, there is a native windows version that can be compiled with VS. The Windows SDK 7.1 is all that is needed. If there is interest, that source code can be either included in a separate directory in this project, or as a separate project. Add an issue if you are interested in the native windows version being made available.
This code is licensed under the GPLv2 open-source license contained in gpl-2.0.txt and copyright David C. Rankin, 2019.